<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../vue.js"></script>
</head>
<body>
  <div id="app">{{msg}}
    <!-- <h1>{{num}}</h1> -->
    <!-- <h1>值为null...{{s1}}</h1> -->
    <!-- <h1>值为字符串的null...{{s2}}</h1> -->
    <h1>key为null的null...{{null}}</h1>
    <!-- <h1>{{undefined}}</h1> -->
  </div>

  <script>
    Vue.config.productionTip=false
    const vm= new Vue({
      // el:'#app',
      data(){
        return {
          msg:'hello Vue',
          num:2,
          s1:null,
          s2:'null',
          // null:'null',
          null:'undefined',
          // undefined:undefined,

        }
      },
    })
    vm.$mount('#app')

    // new Vue({
    //   data: {
    //     msg: "hello Vue"
    //   }
    // }).$mount("#app") 

  </script>
</body>
</html>